The invention relates to methods of diagnosing pancreatitis.
The pancreas is a large, elongated gland situated transversely behind the stomach, between the spleen and the duodenum. The pancreas consists of two portions, both of which are crucial for regulation of metabolism and for digestion. The endocrine portion of the pancreas (pars endocrina), which contains the islets of Langerhans, produces and secretes both insulin and glucagon directly into the bloodstream. These two hormones play a major role in the regulation of carbohydrate metabolism. The exocrine portion of the pancreas (pars exocrina) consists of secretory units (pancreatic acini) which produce and secrete pancreatic juice into the pancreatic duct and thence into the duodenum. Pancreatic juice contains approximately twenty known enzymes and isoenzymes, including glycosidase, proteases, lipases, and nucleases, which are essential for digestion of carbohydrates, fats, proteins, and other food components.
Pancreatitis is an inflammation of the pancreas accompanied by autodigestion of pancreatic tissue by its own enzymes. Pancreatitis may be either acute or chronic. Acute pancreatitis is associated with a sudden onset of abdominal pain, nausea, and vomiting. Predisposing conditions for acute pancreatitis include chronic alcoholism, gallstones, hypercalcemia, hyperlipoproteinemia, blunt abdominal trauma, and penetrating peptic ulcer. Predisposition may also be inherited as an autosomal dominant trait.
Chronic pancreatitis, which may be accompanied by recurrent attacks of acute pancreatitis, is usually associated with recurrent, chronic abdominal pain, progressive fibrosis and loss of exocrine (steatorrhea) and endocrine (diabetes mellitus) function, though the disease may also be asymptomatic. Although the specific pathogenesis of chronic pancreatitis is unknown, most cases of the disease suggest that obstruction of the pancreatic ducts may play a crucial role. Forms of acute or chronic pancreatitis include acute hemorrhagic pancreatitis, chronic calcific (calcareous) pancreatitis, centrilobular pancreatitis, chronic relapsing pancreatitis, perilobular pancreatitis, and purulent pancreatitis.
The majority of individuals who develop acute or chronic pancreatitis are alcoholics. Pancreatitis may also result from a slow-growing mucinous pancreatic cystadenoma or congenital anomalies such as annular pancreas or pancreas divisum, presumably as a result of intermittent ductular obstruction. Occasionally, infections that involve the pancreas, such as those caused by mumps virus, Salmonella typhi, or streptococci, produce an acute suppurative pancreatitis. Pancreatitis may also develop in malnourished individuals in the third world (tropical pancreatitis) and in response to an abrupt increase of food intake after prolonged fasting. Some evidence suggests a link between episodes of acute pancreatitis and a variety of drugs including azathioprine, thiazides, sulfonamides, furosemide, estrogens, tetracycline, and cytosine arabinoside. There is also some suggestion that corticosteroids, L-asparaginase, ethacrynic acid, phenformin, and procainamide may produce pancreatic inflammation.
Pancreatitis is conventionally diagnosed by physical examination and by evaluation of levels of amylase, lipase, or trypsin in serum, or the ratio of amylase to creatinine in serum. None of these conventional diagnostic tests is specific for pancreatitis. For example, increased serum amylase may also be due to cholecystitis, hepatitis, intestinal obstruction, mesenteric thrombosis, parotitis, perforated duodenal ulcer, or a ruptured aortic aneurysm. Increased levels of serum trypsin can be caused by chronic renal failure. Similarly, the ratio of amylase to creatinine in serum may be elevated by uremia or acute tubular damage.